Air streams often carry particulate material therein. In many instances, it is desirable to remove some or all of the particulate material from an air stream. For example, air flow stream to engines for motorized vehicles or to power generation equipment; gas streams directed to gas turbine systems; and air streams to various combustion furnaces, often include particulate material therein. Also, liquid streams into engine lube systems or hydraulic systems also carry particulate matter within it. If the particulate material reaches the internal workings of the various mechanisms involved, it can cause substantial damage to the equipment. Thus, it is preferred that for such systems, the particulate material be removed from the air or liquid flow upstream of the engine, turbine, furnace, or other equipment involved. A variety of air filter, fluid filter, and liquid filter arrangements have been developed for particulate removal. In general, however, continued improvements are sought.